Cyclin D mediates tolerance of genome-doubling in cancers with functional p53.

Background: Aneuploidy and chromosomal instability (CIN) are common features of human malignancy that fuel genetic heterogeneity. Although tolerance to tetraploidization, an intermediate state that further exacerbates CIN, is frequently mediated by TP53 dysfunction, we find that some genome-doubled tumours retain wild-type TP53. We sought to understand how tetraploid cells with a functional p53/p21-axis tolerate genome-doubling events. Methods: We performed quantitative proteomics in a diploid/tetraploid pair within a system of multiple independently derived TP53 wild-type tetraploid clones arising spontaneously from a diploid progenitor. We characterized adapted and acute tetraploidization in a variety of flow cytometry and biochemical assays and tested our findings against human tumours through bioinformatics analysis of the TCGA dataset. Results: Cyclin D1 was found to be specifically overexpressed in early but not late passage tetraploid clones, and this overexpression was sufficient to promote tolerance to spontaneous and pharmacologically induced tetraploidy. We provide evidence that this role extends to D-type cyclins and their overexpression confers specific proliferative advantage to tetraploid cells. We demonstrate that tetraploid clones exhibit elevated levels of functional p53 and p21 but override the p53/p21 checkpoint by elevated expression of cyclin D1, via a stoichiometry-dependent and CDK activity-independent mechanism. Tetraploid cells do not exhibit increased sensitivity to abemaciclib, suggesting that cyclin D-overexpressing tumours might not be specifically amenable to treatment with CDK4/6 inhibitors. Conclusions: Our study suggests that D-type cyclin overexpression is an acute event, permissive for rapid adaptation to a genome-doubled state in TP53 wild-type tumours and that its overexpression is dispensable in later stages of tumour progression.

Obese and fit adolescents have lower blood pressure levels than obese and unfit counterparts.

AIM: The aim of the study was to assess the effects of physical fitness on the relationships between body mass index (BMI) and body fat (BF) on blood pressure (BP) levels. METHODS: Cross-sectional study conducted in 25 schools of Lisbon (Portugal), including 2041 boys and 1995 girls aged 10-18. BF was assessed by bioimpedance. Cardiovascular fitness was assessed by the 20-meter shuttle run and classified as fit/unfit. Obesity (BMI or BF defined) was defined according to international criteria. RESULTS: In both sexes, BMI was positively related with systolic and diastolic BP, while BF was only positively related with diastolic BP z-scores. No interaction was found between fitness and BMI categories regarding BP levels, while for BF a significant interaction was found. Being fit reduced the BF-induced increase in the Odds ratio (OR) of presenting with high BP: OR (95% confidence interval) 1.01 (0.73-1.40) and 0.99 (0.70-1.38) for overweight and obese fit boys, respectively, the corresponding values for unfit overweight and obese boys being 1.33 (0.94-1.90) and 1.75 (1.34-2.28), respectively. The values were 0.88 (0.57-1.35) and 1.66 (0.98-2.80) for overweight and obese fit girls, respectively, the corresponding values for unfit overweight and obese being 1.63 (1.12-2.37) and 1.90 (1.32-2.73) respectively. No interaction was found between fitness and BMI-defined overweight and obesity. CONCLUSION: Being fit reduces the negative impact of BF on BP levels and high BP status in adolescents. This protective effect was not found with BMI.

Dexamethasone inhibits vascular smooth muscle cell migration via modulation of matrix metalloproteinase activity.

BACKGROUND: Dexamethasone (DEX) has been shown to inhibit development of neointimal hyperplasia in rats. We hypothesize that DEX inhibits neointimal hyperplasia by altering matrix metalloproteinase (MMP) activity, resulting in inhibition of smooth muscle cell migration. METHODS: Rat aortic smooth muscle cells (RASMC) were harvested and cultured for two to four passages. A migration assay was performed in a Boyden chamber with chemoattractant (platelet-derived growth factor) and varying concentrations of DEX (10(-9) to 10(-5) M). The number of migrated cells was counted under light microscopy. Zymography was performed on culture media to assess MMP activity, and Western blotting was performed to assay MMP and levels of tissue inhibitors of MMPs (TIMPs). RESULTS: DEX progressively inhibited RASMC migration in a dose-dependent fashion. This effect was statistically significant for concentrations of 10(-7) to 10(-5) M (P < 0.0005). Zymography showed that DEX inhibits MMP-2 activity in a dose-dependent manner. Western blots indicated that total MMP-2 secretion was inhibited and that TIMP-2 secretion was increased by DEX. CONCLUSIONS: DEX inhibits platelet-derived growth factor-induced migration of RASMCs and MMP-2 activity in vitro. Our data suggest that DEX suppresses MMP activity and secretion, resulting in the inhibition of smooth muscle cell migration. This may explain the mechanism by which DEX inhibits neointimal hyperplasia.

Minimal incision abdominal aortic aneurysm repair.

PURPOSE: The use of a limited incision for abdominal aortic aneurysm (AAA) repair was evaluated, and its outcome was analyzed in comparison to laparoscopic-assisted and standard open repair. METHODS: Eleven patients who had an AAA that required a tube graft underwent minimal incision (MINI) repair. The procedure consisted of a standard endoaneurysmorrhaphy performed through an 8- to 10-cm minilaparotomy. Clinical characteristics, in-hospital outcomes, and total in-hospital charges for this procedure were then compared with those of comparative groups of patients who had undergone repair of AAA by means of a laparoscopic-assisted (LAP) approach or a standard open (OPEN) technique. RESULTS: MINI repair was successfully completed in all 11 patients. Patients in the three groups were comparable for age, sex, risk factors, and aortic dimensions. The mean values for operative time, blood loss, length of hospital stay, and total hospital charges for the three comparison groups were: 129. 7 minutes (MINI) vs. 244.8 minutes (LAP)*, 209.9 minutes (OPEN)*; 522.7 mL (MINI) vs. 1214.7 mL (LAP), 1795.8 mL (OPEN)*; 5.18 days (MINI) vs. 18.7 days (LAP), 17.4 days (OPEN); $22,692 (MINI) vs. $59, 922 (LAP)*, $62,324 (OPEN)* (*P <.05). Local complications occurred in 18.2% of patients who underwent MINI repair, 23.5% of patients who underwent LAP repair, and 29.7% of patients who underwent OPEN repair (P = not significant). Patients undergoing minilaparotomy demonstrated decreased compromise of gastrointestinal function, with a decreased need for postoperative fluid resuscitation (6799.7 mL [MINI], 7781.8 mL [LAP] vs. 11061.1 mL [OPEN]*) and shortened nasogastric tube decompression (1.6 days [MINI], 1.5 days [LAP] vs. 4.1 days [OPEN]*; *P <.05). CONCLUSION: MINI repair is a technically feasible technique that combines the benefits of minimally invasive surgery with those of conventional open repair with few, if any disadvantages. Facility of the procedure, combined with the potential cost benefits, encourages further study for consideration of this technique as a viable alternative for the management of AAAs.

Laparoscopically assisted abdominal aortic aneurysm repair.

Since the advent of laparoscopy, the sweeping changes seen in general surgery have not been paralleled in vascular surgery. However, the application of laparoscopic techniques to intraabdominal vascular procedures has now progressed from the animal laboratory to the clinical arena. Initial experience with laparoscopically assisted aortic bypasses for occlusive disease has led to the development of procedures for aneurysmal disease. This article reviews the current clinical experience in the evolving technique of laparoscopically assisted abdominal aortic aneurysm repair.

Laparoscopically assisted abdominal aortic aneurysm repair.

Since the first description of abdominal aortic aneurysms by sixteenth-century anatomist Vesalius, the history of this disease has reflected the remarkable progress of vascular surgery. From initial attempts of ligation and sclerosis to the recent advances of endovascular and laparoscopic repair, present-day vascular surgeons are supplied with a technically evolving choice of therapeutics. None of these procedures is mutually exclusive; currently, great interest lies in the use of laparoscopy to provide extraluminal control at the neck of aneurysms, to work with endoluminal grafts, and to control collateral vessel endoleaks. Laparoscopic vascular surgery must not be introduced into the clinical arena based only on the assumption that it is feasible. Clearly, it is a technically challenging procedure with a steep learning curve that requires specialized instrumentation and sophisticated laparoscopic suturing capability; however, with continued investigation, including prospective randomized trials, laparoscopic treatment of aortic aneurysms may become a standard option for high-risk patients.

Reduced capacity to inhibit elastase in abdominal aortic aneurysm.

BACKGROUND: Loss of elastin in the aortic wall is an early event in abdominal aortic aneurysm (AAA). An imbalance in the protease-antiprotease system is proposed to be one of the factors that promote connective tissue destruction. We hypothesize that plasma from AAA patients will have a reduced inhibitory capacity in comparison to normal controls. MATERIALS AND METHODS: Using an assay we developed, plasma (10 microliters), collected from AAA patients (n = 14) and normal controls (n = 13), was added to the elastase inhibition assay containing succinylated elastin substrate. The reaction was initiated with 13.9 units porcine pancreatic elastase (PPE). Elastase activity in the presence and absence of plasma was compared. Plasma elastase was also determined using the Merck PMN-elastase kit. RESULTS: The relative activity of exogenous elastase (%) in the presence of AAA plasma (n = 14, mean age 73.4 years +/- 1.7 SEM) was 42.59% +/- 4.3 SEM, while that in the presence of control plasma (n = 13, mean age 73.9 years +/- 2.1 SEM) was 10.23% +/- 2.1 SEM (P < 0.0001). Analysis of plasma elastase (microgram/L) indicated that there was no significant difference between normal (n = 9, 207.33 microgram/L +/- 58.67 SEM) and AAA (n = 9, 145.34 microgram/L +/- 29.54 SEM) (P = 0.359). CONCLUSION: There is a significant reduction in the plasma inhibitory capacity of elastase in AAA patients in comparison to normal controls, though plasma elastase level was not significantly different. The data presented here give experimental evidence to the protease-antiprotease imbalance in AAA patient plasma and may lead to the development of a measurable parameter to monitor AAA.